>In my program the date of the day is very important, how can I do so that the user does NOT access Windows and change it?
>Note: my program takes the windows date

You want your application to prevent the user from having access to change the date in Windows? I would not recommend that.

Normally it is done at the server level

https://www.sevenforums.com/tutorials/113557-date-time-allow-prevent-users-groups-changing.html

Or get the date from the server rather than the local station. Create a textfile on the server, and get the date of the file.